Purpose: The objective of this study was to assess the role of different packaging in the inactivation of Bacillus amyloliquefaciens TMW 2.479 Fad 82 spores in HEPES buffer (pH 7) during PATP treatment.
Methods: Experiments were conducted using a laboratory scale high pressure unit. Propylene glycol was used as the pressure transmitting fluid. Aliquots (2.25ml) of B. amyloliquefaciens spore samples (~2.09 x 106 spores/ml) used as a surrogate for Clostridium botulinum were packaged into polyethylene pouch, polyethylene tube , and semi-rigid polypropylene cryogenic vial. The spore samples with minimal headspace were pre-heated at 45°C before loading into pressure vessel. The samples were treated at 600 MPa and 105°C from 0 to 20 minutes holding time in triplicate. Processed samples were cooled immediately in ice water before counting survivors.
Results: The computed D-values from linear portion of the survivor curve for B. amyloliquefaciens spores treated in pouch, vial, and tube packages were 2.92, 2.09, and 2.83 minutes, respectively. Within the experimental conditions of the study, spores processed in semi-rigid vials had 0.48 to 0.9 log more inactivation (P < 0.05) than those processed in pouch and tube in 5, 10 and 20-minute treatments. The difference in spore inactivation could be attributed to uncontrolled experimental variability in different polymer properties. In summary, in comparison to other processing variables (such as pressure, temperature and holding time), the packaging type did not have major contribution to spore reduction during PATP treatment.
Significance: The findings of the study demonstrate that the packaging type may introduce some variability in PATP spore inactivation studies. A more systematic study is needed to determine the relationship between process efficacy and package material, thickness and geometry.